Aviation gas turbine lubricants



additives T Alfred H. Matuszak, WestfieldpErnest v. wn e Cr m 7ford,;and Walter W. Gleason, Roselle, NJ.,.assignors 'to Esso Researchand'Engineering Company, a .corpo-f, ration of Delaware v I No Drawing.Filed Dec. '2-4, 1956, Ser. No. 630,060 7 AClaims. Cl. 252-493) Thisinvention relates to synthetic lubricating compo- 'sitions.Particularly, the inventionrelates tolubricating compositionscomprisinga synthetic ester lubricating oil and minor amounts of certainadditives which improve the load carrying ability of the synthetic oil.

"Synthetic-ester lubricating oils are known to the art. 'In general,these oils" are characterized by viscosity properties that areoutstandingat both low andhigh temperatures, especially when compared tomineral oils. In recent years,';th'e synthetic ester oils have become ofincreasing importance in the field of lubrication, and one of the mostimportant current applications of. such compounds is in the lubricationof aviation gas-turbine systerns such as are use'd'in'the turbo}jet1 orturbo-prop 'type' ofaircraftq" Howeverfiri general, the load-carrying'ability of f;t hese ester oilsis "notparticularly high. Because ofthe'increasing severity of theconditions prevailing in the lubricationof aviation gas-turbine systems, itis highly desirable to'form syntheticester lubricating compositions having higherload-carrying' ability thanis inherent in the ester oil itselfgf invention, therefore,isconcerned'with synthetic ester oils containing for increasingjthe'load-carryingability of the g In generaL-the compositionsof thisinventionwill comprise'a synthetic ester lubricating oil and minorloadcarrying improving amount'sof saturated aliphatic dica'rboxylicacidscontaining 6 to '10carbon atoms per molecule Although these dicarboxylicacids are very elfective asrlo'ad-carryin g agents, the amount in whichthey canfbje used is limited; since *they are not generally soluble inester oils in "amountsjgreater than 0.10% by weigh'tp Itfhas'also, beenfound that small amounts of an phosphate landhalogen substituted alkylphosphorus compounds-are also very eflfectivejin'increasing theloadcarryingability of the ester lubricant. Surprisingly, it has beenfurther found that the combination of the di- 2,938,871 .pg nted May731;: 9-

elude di-Z-ethylhexyl sebacate, 'di-n-nonyl adipate, di-ntridecylazelate, di-n-heptylisosebacate, di-C Oxo trimethyl adipate, (ii-COXopimelate, etc. The diesters prepared from the Oxo alcohols; which areisomeric mixtures of highly branched-chain aliphatic primary alco- Yhols, are particularly desirable. The Oxo alcohols have a very highdegree; of branching in the'hydrocarbon chain, which results in diesteroils-having low 'pour'points and low viscosity at low temperature. Thesealcohols areprepared from olefins, such as polymers and copoly- I mersof C and C monoolefins, which are reacted with hydes.

carbon monoxide and hydrogen, in'the presenceof a cobalt-containingcatalyst such as a cobalt carbonyl catalyst, at temperatures of about300? to 400- F., and under pressures of about 1000 to 3000 p.s.i., toform alde- The resulting aldehyde product is, then hydrogenated to formthe alcohol which is then recovered from the hydrogenation product.

The dicarboxylic acids which may be used as loadcarrying agentsarethose' saturated aliphatic dicarbcx-ylic acids having 6' to 10earbonatoms per molecule. These acids include adipic acid, pim'elicacid, suberic acid, azelaic acid, sebacic acid and isosebacicacid- Theisosebacic acid isa mixture of C acids comprising about 60 to 90 wt.percent of a-ethylsuberic acid, about5'to 25 wt. percent'of a,a'-diethyladipic acid, andabout 5 to 15 wt. percent of sebacic acid. A typicalsuch acid will contain about 75 wt. percent of oz-ethyl suberic acid,about-15 wt. percent of ,a'-diethyl adipic acid and about 10 wt. percentof sebacic acid.

' The aryl. phosphates useful in this; invention are those 1 compoundswhich have the following general formula:

carboxylic acid with small amounts of (a) the halogen- V substitutedalkyl phosphorus compound, or (b) a mix ture of both the aryl phosphateand the halogen-substituted alkyl phosphorus compounds, results in anadditive combination having a much greater effect on the loadcarryingability of the synthetic ester lubricant than would be expected from themere addition of the individ- 'ual. efiect of each component. V I Theesteroilsused in the compositions of this invention include diesters ofsaturated aliphatic dicarboxylic acids esterified with alcohols. Thesediestersv have the general formula: I a

' ROOC-R COOR- wherein R represents a straight-chain or branched-chainalkyl radical of an alkanol hayingabout 7 to 13 carbon atoms, R -is astraightorvbranched-chain C to C alkylene radical of a dicarboxylicacid, and the total number of carbon atoms in the molecule=being about20 to 36, preferably 22 to 26. Examples of suchdieste'rs inwherein eachR is a-raclical sele'ctedfrom the, group consisting'of hydrogen andalkyl groups containing about l'to 4 carbon atoms, e.'g. methyl groups.Examples of such phosphates include triphenyl phosphate, phenyldicresylphosphate, tricresylphosphate, methyl di-tert. butyl phosphate,etc.

The halogen-substituted alkylphosphorus compounds 1 useful in thisinvention may be d ivided into three gen:

eral classes as follows: j 1 Halogen (e.g. chlorine) phosphonates whichinclude saturated and unsaturated, 'mo'no, -di and trihalogensubstituted alkyl phosphonates having the general forethyl) Iethyl 'phosphonate; bis(4-ichloropentyl) Table III Composition ofLubricant (Parts) Diester Oil: 7

Di-2-ethylhexyl sebacate 55 70 30 100 03 0x0 Arc-late C Oxo Adipate. 4501; 0x0 adipate 30 20 10 Dibasie Acid:

Iso-sebacic acid 70.1 Azelaic acid Adlpic Acid Aryl Phosphate:

Triphenyl phosphate 1. 0 Phenyl dicresylghosphate 3.0 1. 0 1.0Halohosphorus Gompound: Methyl di-tert. butyi phosphate; Tris(2-chloroethyl) hos h 0.3 0.2 BIsOZ-chloroethyl) vinyl phosphonate. 0. 5Bisw-chloroethyl) ethyl Iphosphonate. 0. 6 Tris 2-o loroethyl) phosphitp0. 3 Other additives:

Phenothiazine 1 Phenyl alpha naphthylamine 1 1 1 What is claimed is: 1.A synthetic ester lubricating oil composition having improvedload-carrying ability, which comprises a major proportion of a diesterhaving the formula R0\ B0P=O wherein R, R and R" are selected fromthe-group consisting of aliphatic hydrocarbon radicals andhalogensubstituted aliphatic hydrocarbon radicals, each of said radicalscontaining 1 to 5 carbon atoms and at least one of said radicals beinghalogen-substituted.

2. A composition according to claim 1 wherein said dicarboxylic acid issebacic acid and wherein said halogen-containing phosphonate isbis(fi-chloroethyl) vinyl phosphonate.

3. A synthetic ester lubricating oil composition having improvedload-carrying ability, consisting essentially of a diester having theformula R0OCR --C0OR where in R represents an alkyl radical of analcohol having about 7 to 13 carbon atoms, R is a C to C alkyleneradical of a dicarboxylic acid, and the total number of carbon atoms inthe molecule being about 20 to 36; about 0.01 to 0.10 wt. percent of asaturated aliphatic dicarboxylic acid containing about 6 to 10 carbonatoms per molecule, about 0.5 to 5.0 wt. percent of an aryl wherein eachR is a radical selected from the group consisting of hydrogen and alkylgroups containing about 1 to 5 carbon atoms; and about 0.1 to 0.8 wt.percent of a halogen-containing phosphonate having the general formula:

wherein R, R and R" are selected from the group consisting of aliphatichydrocarbon radicals and halogensubstituted aliphatic hydrocarbonradicals, said radicals containing 1 to 5 carbon atoms and at least oneof said radicals being halogen-substituted.

4. A composition according to claim 3 wherein said dicarboxylic acid issebacic acid; said aryl phosphate is tricresyl phosphate; and whereinsaid phosphonate is bis(fl-chloroethyl) vinyl phosphate.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Lubrication Engineering, August 1952, pages 97-200.

1. A SYNTHETIC ESTER LUBRICATING OIL COMPOSITION HAVING IMPROVEDLOAD-CARRYING ABILITY, WHICH COMPRISES A MAJOR PROPORTION OF A DIESTERHAVING THE FORMULA
 3. A SYNTHENIC ESTER LUBRICATING OIL COMPOSITIONHAVING IMPROVED LOAD-CARRYING ABILITY, CONSISTING ESSENTIALLY OF ADIESTER HAVING THE FORMULA ROOC-R1-COOR WHEREIN R REPRESENTS AN ALKYLRADICAL OF AN ALCOHOL HAVING ABOUT 7 TO 13 CARBON ATOMS, R1 IS A C4 TOC8 ALKYLENE RADICAL OF A DICARBOXYLIC ACID, AND THE TOTAL NUMBER OFCARBON ATOMS IN THE MILECULE BEING ABOUT 20 TO 36, ABOUT 0.01 TO 0.10WT. PERCENT OF A SATURATED ALIPHATIC DICARBOXYLIC ACID CONTAINING ABOUT6 TO 10 CARBOM ATOMS PER MOLECULE, ABOUT 0.5 TO 5.0 WT. PERCENT OF ANARYL PHOSPHATE HAVING THE GENERAL FORMULA: